Such cover arrangements, for example to be used on street drains or the like, are known. For instance, the patent DE 3523423 C1 discloses a hinged gully top consisting of a frame and a grating, constructed so that hinge bolts can be inserted or screwed into the frame from outside. Hence it is a simple matter to open the grating by means of these hinges. This offers the advantage that, for example during cleaning and maintenance work, the grating does not need to be lifted completely out of the frame, but when necessary can simply be pivoted upward. The result is not only a reduction of the effort expended and the risk of injury during cleaning and maintenance work, but in addition the grating is secured against theft. The disadvantage of this design is that to disassemble the grating, the frame must be exposed in the hinge region in order to provide access to the hinge bolts. This inevitably involves damage to the adjacent pavement surface and hence a not inconsiderable expenditure of effort and materials in order to remove or exchange the grating. Furthermore, with this design the direction in which the cover arrangement is pivoted when raised must already be taken into account during installation, in order to ensure that the raised cover or grating is not opposed to the oncoming vehicles. A grating raised in such a way would seriously endanger the traffic.
Furthermore, in most of the known hinged cover arrangements there is nothing to prevent vandals from raising the grating or cover, because the cover arrangements can usually be tilted up without any special tool. In this case both the grating, projecting upward from the pavement, and the opening thus left in the shaft cover are a major source of danger.
The patent DE 299 14 492 U1 discloses a shaft cover with hinge bolts that are accessible from inside, which offers the advantage that, for example when the cover is being exchanged, the frame need not be exposed in the region where the hinge bolts are being attached. In other respects, this design involves the same disadvantages as the shaft covers previously described.
The patent DE 1834483 U1 discloses a hinge device consisting of 2 joint cogs, each of which lies in a cavity within a separate bracket on a grating. These two brackets are set into corresponding receptacles on the frame, so that the joint cogs lying loosely in the cavity slide partially into corresponding cavities within the frame and thus connect the grating or cover firmly to the frame. The joint cogs here are, for example, spherical in shape and are rolled by gravity into the associated cavities within the frame, or they consist of cylinders supported on springs, which are pressed into the associated frame cavities by the spring force. A disadvantage of this design is that the hinge mechanism for the cover arrangement consists not of a single part but rather of several individual elements. These must be installed in the cover device after it has been cast, which is cost-intensive. Furthermore, the presence of extra parts also increases the likelihood of faults developing, because such parts can be lost, and this system is very vulnerable to dirt, because such small parts (springs, balls) are readily harmed by corrosion and dirt. Another disadvantage is that once the grating has been installed, great effort is required to remove it. And in this design, again, there is the problem that the installation orientation depends on the direction of vehicle travel. If the traffic direction changes, great effort is required to adapt the grating accordingly.